Method for inserting cylinder liners into internal combustion engine cylinder blocks

ABSTRACT

A robotic system for inserting cylinder liners into the cylinder block from an internal combustion engine includes an articulated robot arm for cycling an end effector between a dunnage unloading position and a cylinder insertion position. The end effector, which is attached to the robot arm, picks liners from dunnage and places the liners in the cylinder bores of the cylinder block. The end effector includes remotely deployable combination teeth for gripping the liners to permit removal from their dunnage and for aligning the end effector and liner into the cylinder bores to permit insertion of the liners.

This is a division of application Ser. No. 08/131,068, filed Oct. 4,1993, now U.S. Pat. No. 5,471,738.

BACKGROUND OF THE INVENTION

This invention relates to a mechanical system for inserting cylinderliners into the cylinder bores of an internal combustion cylinder block.

DESCRIPTION OF THE PRIOR ART

Although some automotive engines having aluminum cylinder blocks havebeen constructed without separate liners in the cylinder bores, it iscustomary to provide such liners, which are typically constructed ofcentrifugally cast iron. Liners may be pressed in place or,conventionally, the aluminum cylinder block is preheated and, takingadvantage of aluminum's high coefficient of thermal expansion, an ironliner may be slipped into the heated block such that once the aluminumhas cooled to the normal operating temperature of the block or below,the liner is gripped tightly by the aluminum surrounding the liner suchthat the liner cannot separate from the cylinder block. Unfortunately,the insertion of an iron liner into a heated aluminum cylinder block isfrequently a difficult proposition for a human engine assembly operator.The liners must be inserted quickly and with one fluid motion, inasmuchas heat transfer from the parent bore to the liner will quickly causethe liner to expand and the aluminum to cool to the point where theliner cannot be inserted. This requires that the liner be positioned notonly quickly, smoothly, and in a continuous motion, but also withoutcocking of the liner, which occurs when the centerline axis of the linerand the centerline axis of the bore into which it is being inserted arenot collinear. If the liner becomes cocked in the cylinder bore, it willnot slide completely into the bore because the liner will become jammedas the heat from the cylinder block flows into the liner, expanding theliner and causing a simultaneous contraction of the aluminum cylinderblock. An additional drawback to the use of human production operatorsfor inserting liners resides in the fact that the cylinder blocks mustbe heated to well above 100° centigrade and, as a result, the linerinstallation area is quite uncomfortable for a human operator.

A system according to the present invention avoids the shortcomings ofmanual insertion techniques by providing a precise liner picking andinsertion system which assures that the liners will be properly engagedwith the cylinder bores and smoothly inserted so as to prevent cockingand incomplete insertion of the liners.

SUMMARY OF THE INVENTION

A robotic system for inserting cylinder liners into the cylinder blockof an internal combustion engine includes an articulated robot arm forcycling an end effector between a dunnage unloading position and a linerinsertion position. An end effector is attached to the robot arm. Theeffector picks liners from dunnage and places the liners into thecylinder bores of the cylinder block. The end effector includes remotelydeployable combination teeth for gripping the liners to permit removalfrom their dunnage and for aligning the end effector into the cylinderbores to permit insertion of the liners without cocking or jamming. Theend effector is attached to the robot arm by means of a remotelycontrollable compliance device. The compliance device is maintained in afree position when the end effector is picking liners from dunnage, andas well as when the end effector is inserting the liners into thecylinder block. Conversely, the compliance device is in a locked, ornoncompliant, position when the robot arm is translating the endeffector from the dunnage to the cylinder block. As used herein, theterm "dunnage" means a tray-like conveyance for transporting cylinderliners from a manufacturing or storage location to an engine assemblyline. The compliance device for attaching the end effector to the robotarm preferably comprises an axially actuatable camming slide.

An end effector according to the present invention preferably comprisesat least one generally cylindrical barrel having remotely deployablecombination teeth extending radially outwardly from the cylindricalsurface of the barrel. The combination teeth not only grip the insidediameter of the cylinder liners but also provide a means for aligningthe end effector into the cylinder bores to permit insertion of theliners into the cylinder block.

According to yet another aspect of the present invention, a method forinserting cylinder liners into the cylinder block of an internalcombustion engine comprises the steps of heating the cylinder block toexpand the cylinder bore area sufficiently to permit installation of theliners, picking a plurality of cylinders from dunnage by means of arobotic device, and inserting the liners into the heated block with therobotic device. Preferably, all of the cylinders in one bank of thecylinder block will receive liners simultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system according to the present invention in whicha robot arm has positioned the end effector in the dunnage pickingposition.

FIG. 2 is similar to FIG. 1 but illustrates the robot arm and endeffector in the liner installation mode.

FIG. 3 illustrates an end effector according to the present invention asit grips a cylinder liner to remove the liner from dunnage.

FIG. 4 illustrates the end effector of FIG. 3 in the liner positioningmode.

FIG. 5 illustrates a compliance device associated with the end effectorin the locked mode, as when the compliance device is being translatedfrom the dunnage picking to the cylinder installation mode by the robotarm.

FIG. 6 is a sectional view of the end effector and liner of FIG. 4 takenalong the direction of the lines 6--6 of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1 and 2, a series of engine cylinder blocks 20 isprogressing along an assembly line on fixtures 24. Articulated robot arm14 has the task of cycling end effector 16 between a dunnage pickingposition in which cylinder liners 10 are removed from dunnage tray 12and a liner insertion position in which the cylinder liners slide intothe cylinder bores 22 of cylinder blocks 20. Preferably the outsidesurface of the each liner, as well as the surfaces of the parent bores,are machined and finished to provide approximately 0.0007 in. totaldiametral clearance with the cylinder block heated to 365° F. (with a15° tolerance), and the liner at room temperature.

Cylinder blocks 20 are positioned by fixtures 24, which alternativelypresent the cylinder head mating surfaces of the banks of cylinders 22in a horizontal orientation to robot arm 14 and end effector 16. Asshown in FIG. 2, a first cylinder bank is in the vertical position forinsertion of the liners 10 into cylinder bores 22. Following theinsertion of liners into the first bank, end effector 16 will be rotatedso that a second group of liners will be positioned for insertion intothe block. At this time, the block will be rotated by fixture 24 aboutthe block's longitudinal or crankshaft axis such that the second bank ofcylinders is in a vertical position, with the cylinder head matingsurface horizontal. As shown in FIG. 1, end effector 16 is rotatable ona vertical plane so as to allow the picking and insertion of eightcylinder liners from dunnage into the engine block.

Details of the operation of end effector 16 are shown in FIGS. 3-6. Whenend effector 16 and robot arm 14 are removing liners from dunnage, it isdesirable to allow compliance between end effector 16 and robot arm 14.To this end, limited freedom of movement is provided between motor plate35, which is rigid with end effector mounting flange 26, which ismounted upon base plate 46, and compliance motor 28 and socket 34 fromwhich the balance of the end effector depends. As shown withparticularity in FIGS. 3 and 5, socket plate 34 is engageable viacompliance plunger 32, which is operated by compliance motor 28. Airintroduced into lines 30 will cause a piston (not shown) withincompliance motor 28 to pull compliance plunger 32 upwardly such thatsocket plate 34 is clamped tightly against motor plate 35. In thismanner, end effector 16 is not allowed to swing freely from motor plate35. When compliance motor 28 has positioned compliance plunger 32 in itslower, or unlocked position, pin 44, which extends from socket plate 34through an aperture in motor plate 35, will allow a limited amount ofcompliance, while preventing rotation of socket plate 34 with respect tomotor plate 35. Compliance plunger 32 is maintained in the lockedposition when robot arm 14 is moving end effector 16 from the dunnagepicking position (FIG. 1) to the liner insertion position (FIG. 2).Robot arm 14, as well as compliance motor 28 and gripper motor 36 may beoperated by a robot controller drawn from the class of appropriatecontrollers known to those skilled in the art and suggested by thisdisclosure.

The positions of combination teeth 18 within end effector 16 are shownfor various conditions in FIGS. 3, 4, and 6. Beginning with FIG. 3,liner 10 is being engaged by end effector 16, which has a plurality ofbarrels 42, each having a plurality of combination teeth 18 extendingradially outwardly from the cylindrical surface 42a of barrel 42.Combination teeth 18 have a larger diameter surface 18a, which isintended to contact not only the inner diameter of cylinder liners 10,but also the parent bore 22 of cylinder block 20. In the liner pickingposition shown in FIG. 3, surfaces 18a of combination teeth 18 aretightly clamped against the inside diameter of cylinder liner 10 bymeans of a plurality of plunger wedges 40 which are carried upon gripperplunger 38. Plunger 38 is controlled by gripper motor 36, which issupplied with air or other working fluid by means of lines 39. Ineffect, plunger 38 and wedges 40 comprise an axially actuatable cammmingslide. As shown in FIGS. 3 and 4, when plunger 38 is moved into adownward position away from gripper motor 36, combination teeth 18 willbe caused to move radially outwardly because of the interaction ofwedges 40 and cam surfaces 18b. As a result, combination teeth 18 willgrip on the inside of cylinder liner 10, as shown in FIG. 3. As shown inFIG. 4, further downward movement of wedges 40 will relocate combinationteeth 18 radially outward to the position wherein they can pilot uponthe parent bore of the cylinder 22 while holding cylinder liners 10 bybearing upon end surface 10a of cylinder liner 10.

Cylinder liners 10 move upon end effector 16 from the position shown inFIG. 3 to the position shown in FIG. 4 when a bank of individual endeffector units, having picked a set of liners from dunnage, is rotatedfrom the liner picking position, as shown in FIG. 1, in a vertical planeto a setting position in which the liners which have been newly pickedfrom the dunnage are inverted and allow the liner to fall under theforce of gravity to the position shown in FIG. 4 when combination teeth18 are moved to a retracted position by plunger wedges 40, gripperplunger 38, and gripper motor 36.

As shown in FIGS. 4 and 6, insertion of cylinder liners 10 into bores 22is facilitated by combination teeth 18. Section 18a of each tooth pilotsupon parent bore 22, as shown in FIG. 4. This will align both endeffector 16 and liner 10 with parent bore 22. Before end effector 16approaches cylinder block 20, compliance motor 28 will place endeffector 16 in the compliance mode by running compliance plunger 32 tothe downward position. Liners 10 will drop into the cylinder bores,driven solely by the force of gravity, once combination teeth 18 are inthe radially retracted position.

Those skilled in the art will appreciate in view of this disclosure thatmodifications may be made to the system according to the presentinvention while coming within the scope of the appended claims. Forexample, various motors could comprise pneumatic or hydraulic motors, aswell as gear-driven motors, geared rack-type motors, and other devicesknown to those skilled in the art and suggested by this disclosure.Similarly, the choice of the number of plunger wedges employed and theprecise design of the compliance devices and the control systems for thevarious motors and the robot arm may be selected by one skilled in theart, as prompted by this disclosure. Also, it has been determined that,depending upon the degree of automation desired, a robotic controllerincluding appropriate sensing means may be employed to keep the linersin complete engine sets regardless of insertion failures, which may becaused by oversized liners, undersized parent bores, improper blockpreheating, or other causes. All such modifications come within thescope of the appended claims.

We claim:
 1. A method for inserting cylinder liners into cylinder boreslocated within the cylinder block of an internal combustion engine,comprising the steps of:heating the cylinder block to expand an areasurrounding said cylinder bores sufficiently to permit installation ofsaid liners; picking a plurality of liners from dunnage by means of arobotic device with an end effector having a plurality of grippers, eachsaid gripper picking a respective liner, with each said gripper being ina first gripping position wherein a plurality of remotely controllablecombination teeth bear upon the inner diameter of a respective liner;and, inserting each said liner into a respective cylinder bore by meansof said end effector, with each said gripper of said end effector beingin a second gripping position wherein said teeth bear upon an endsurface of a respective liner, with said teeth also serving to pilotsaid respective liner into a respective cylinder bore, said secondgripping position being achieved by retracting said combination teethafter said end effector has been rotated from said first grippingposition to a vertically opposed position, with said inserting stepcomprising inserting all of said liners into a single bank of cylinderbores before picking additional liners from dunnage.
 2. A methodaccording to claim 1, wherein said robotic device comprises a sufficientnumber of grippers to pick sufficient liners to line all of the cylinderbores of said cylinder block with a single trip to dunnage.
 3. A methodaccording to claim 2, wherein said end effector inserts all of theliners for a first cylinder bank of said block and, after the block isrepositioned, inserts all of the liners for a second cylinder bank.
 4. Amethod for inserting a cylinder liner into a cylinder bore locatedwithin the cylinder block of an internal combustion engine, comprisingthe steps of:heating the cylinder block to expand an area surroundingsaid cylinder bore sufficiently to permit installation of said liner;picking a liner from dunnage by means of a robotic device with an endeffector being in a gripper, with said gripper having a first grippingposition wherein a plurality of remotely controllable combination teethbear upon the inner diameter of the liner; and, inserting said linerinto said cylinder bore by means of said end effector, with said gripperof said end effector being in a second gripping position wherein saidteeth bear upon an end surface of said liner, with said teeth alsocontacting the cylinder bores, thereby serving to pilot said liner intosaid cylinder bore.
 5. A method according to claim 4, wherein saidsecond gripping position is achieved by retracting said combinationteeth after said end effector has been rotated from said first grippingposition to a vertically opposed position.